Study On Screening Monascus Spp.Producing Biological Fluorescence Metabolites And Yield Optimization

Red yeast rice is produced by growing Monascus spp.on rice.And it has long been considered as products with a dual medicinal and edible function.Modern medical research shows that red yeast rice has good effect on treating problems like indigestion problems,injuries and high blood pressure.It has health care function to the stomach and spleen,and also is the ideal food colorants and pure natural food preservative.Monascus has many complex metabolic products.It not only can produce primary metabolites such as enzymes,organic acids,fatty acids and amino acids,and also can produce secondary metabolites such as pigment,lovastatin,?-aminobutyric acid,antibiotics,cholesterol inhibitors,citrinin and many Chinese native medicine ingredients.However,some fluorescent compound products from Monascus spp.had received less attention.This article found the two kinds of fluorescent material when studying the physical and chemical properties of 10 kinds red yeast rice collected from jinhua and its surrounding areas,and then the fluorescent material were identified,and we screened and identified high-yield fluorescence material strains from the red yeast,and the production was further increased through the mutant strain,finally optimized the solid-state fermentation conditions,the main results are as follows:(1)The study showed that 10 kinds of red yeast rice collected from jinhua and its surrounding areas had obvious difference in physical and chemical properties,the sensory properties was not big difference,red yeast rice moisture content was different in different samples,the moisture content of YKLSZGH was up to 11.47%,water content was only 6.40%in minimum sample YKLSZ,and the color value was different in samples the largest YKLSZ can reach 781.63 U/g,the smallest QXFH only reach 109.38 U/g.The content of lovastatin varied widely,the content of lovastatin was up to 3.34 mg/kg in YWDX samples.Citrinin qualitative analysis results showed that every sample contains citrinin.(2)Two fluorescent material were isolated by silica gel column chromatography and preparative HPLC,high performance liquid chromatography(HPLC)were used to detect the fluorescent material purity,their structures were analyzed by high resolution mass spectrometry(ESI-HRMS),both of the molecular weight were 356 and 384,two fluorescent material were identified as monasfluore A(MFA)and monasfluore B(MFB).(3)10 Monascus strains were isolated from red yeast rice collected from Jinhua and surrounding area,WZWZ strains of high producting MFA?MFB was obtained by solid fermentation,the content of MFA and MFB in red yeast produced by growing Monascus spp.on rice was measured respectively MFA=3.63 g/kg and MFB=7.29 g/kg.The WZWZ strain was identified as Monascus purpureus by morphology observation.detection indexes of physiological and biochemical as well as the result of ITS genetic sequence amplification and analysis.(4)The UV-induced mutation and compound mutation were applied to study on WZWZ strain,Ultraviolet irradiation of 75 s was the best mutagenesis condition.When LiCl content was 0.04%mutagenic effect was best.Several induced strains were selected for solid-state fermentation and an improved mutant strain numbered WZWZ-24 was obtained.This strain had genetic stability,two fluorescent material production were MFA=4.52 g/kg MFB=8.38 g/kg,the production increased by 24.40%than the original strain.(5)Finally,in order to further improve the production of MFA and MFB,the single factor fermentation experiments were applied to analysis and compare their best carbon source and nitrogen source utilization.Results showed that the mutant strain WZWZ-24 using maltose as additional carbon source and yeast extract as additional nitrogen source had higher yield of MFA and MFB.According to the single factor experiment results of mutant strains WZWZ-24,three main influencing factors of fermentation conditions were tested by L9(33)orthogonal experiment to determine the optimum conditions:pH = 5,maltose 1%,yeast extract 5%.The yield of MFA and MFB can reach 5.18 g/kg and 10.72 g/kg after optimized fermentation.